Bueno les enseñare a instalar virtual box , ya que aveces daba error de los
linux headers entre otras cosas.

Primero nos vamos al a pagina de virtualbox y nos vamos a las descargas
para linux y nos descargamos el:


Y instalamos asi por la consola:

dpkg -i virtualbox-3.1_3.1.8-61349~Ubuntu~intrepid_i386.deb
Y nos tirara error , ahora lo que tenemos que hacer es hacer:

apt-get -f install
Y le damos que si para empesar a descargar lo que nos hace falta

root@bt:~# apt-get -f install
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following extra packages will be installed:
  libdirectfb-1.0-0 libsdl1.2debian libsdl1.2debian-alsa libts-0.0-0
The following NEW packages will be installed:
  libdirectfb-1.0-0 libsdl1.2debian libsdl1.2debian-alsa libts-0.0-0
0 upgraded, 4 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
Need to get 0B/917kB of archives.
After this operation, 2609kB of additional disk space will be used.
Do you want to continue [Y/n]? Y
Y por ultimo le volvemos a dar por consola

dpkg -i virtualbox-3.1_3.1.8-61349~Ubuntu~intrepid_i386.deb
Y esperamos que se instale...

root@bt:~# dpkg -i virtualbox-3.1_3.1.8-61349~Ubuntu~intrepid_i386.deb
(Reading database ... 249518 files and directories currently installed.)
Preparing to replace virtualbox-3.1 3.1.8-61349~Ubuntu~intrepid (using virtualbox-3.1_3.1.8-61349~Ubuntu~intrepid_i386.deb) ...
Stopping VirtualBox kernel module: done.
Unpacking replacement virtualbox-3.1 ...
Setting up virtualbox-3.1 (3.1.8-61349~Ubuntu~intrepid) ...
addgroup: The group `vboxusers' already exists as a system group. Exiting.
Messages emitted during module compilation will be logged to /var/log/vbox-install.log.
Starting VirtualBox kernel module: done.
Y listo lo tenemos instalado y ahora si a tener nuestro laboratorio para pruebas